Elastin represents a major component in several key connective tissues including aorta, large arteries and lung. It is that component which imparts to these tissues their essential property of elasticity, a property which is greatly diminished in diseases such as arteriosclerosis. Pathological studies of elastic tissue have progressed slowly due to a lack in the understanding of the structure, development and function of a normal elastic tissue, especially the protein elastin. The primary objectives of this proposal are concerned with elucidating the primary structure and fibrogenesis of elastin through studies on both soluble and insoluble forms of elastin. Particular attention will be directed toward investigating the biosynthetic steps involved in the transition from a soluble to an insolbule elastin and the areas involved in crosslink formation. Primary sequence studies will be performed on the soluble elastin precursor, tropoelastin, as well as on crosslinked peptides derived from insoluble elastin. All elastin samples will be isolated from the same animal and tissue to permit direct comparative analyses. We also propose to isolate antisera to tropoelastin with the ultimate goal being the development of a radioimmunoassay as a very sensitive technique for tropoelastin detection.